Protection ring for image sensors

Some embodiments relate to a pixel sensor array including a plurality of photosensors arranged in a semiconductor substrate. A protection ring circumscribes an outer perimeter of the pixel sensor array. The protection ring includes a first ring neighboring the pixel sensor array, a second ring circumscribing the first ring and meeting the first ring at a first p-n junction, and a third ring circumscribing the second ring and meeting the second ring at a second p-n junction. The first ring has a first width, the second ring has a second width, and the third ring has a third width. At least two of the first width, the second width, and the third width are different from one another.